Pb1-x Sn x Te is a topological crystalline insulator system with an even number of band Dirac cone at 001,110 and 111 orientations, which represent a trivial system under Kane Mele classification. However, in the past few years, the topological surface states feature in Pb1-x Sn x Te that protected by mirror symmetry drew attention. In contrast to Kane Mele's topological material that protects by time-reversal symmetry. Pb1-x Sn x Te system has a crystal structure phase transition that can drive the topological features of the system. A systematic study on the energy band gap versus temperature and composition shows an interesting regime at x = (0.3-0.7) and T = 70-130 K. (i.e. the topological crystalline insulator regime, phase transition regime). In this paper, we focused on how the following parameters (energy bandgap, temperature T, composition x) connect by three stander models.